The present invention relates generally to a hermetic compressor assembly and, more particularly, to a direct suction compressor assembly having a crankcase mounted within a sealed housing, wherein suction gas is delivered directly to the crankcase from a suction line outside the housing by means of a suction line adaptor.
In general, prior art of hermetic compressor assemblies comprise a hermetically sealed housing having a compressor mechanism mounted therein. The compressor mechanism may include a crankcase or a cylinder block defining a compression chamber therein in which gaseous refrigerant is compressed and subsequently discharged. Typically, and especially in the case of a compressor assembly having a pressurized housing, suction gas returning from a refrigeration system is provided to the compression chamber by means of a conduit extending from outside the housing to the compression chamber within the crankcase. This configuration is commonly referred to as a direct suction compressor assembly. In such a compressor assembly, it is known to introduce suction tubing through the housing and into a suction inlet opening in the crankcase or cylinder block that is in communication with the compression chamber. The portion of the tubing external of the housing may comprise part of a suction accumulator or may constitute a fitting to which a suction line of a refrigeration system may be attached.
In the aforementioned compressor assembly wherein a suction tube leads from an inlet aperture in the crankcase through a hole in the housing, misalignment of the crankcase with respect to the housing may cause the suction tubing to be overstressed when assembled. More specifically, dimension tolerances during machining of component parts of the compressor assembly, particularly the location of apertures and opening through which the suction tube extends, may cause difficulty in assembling the compressor and produce unwanted stress on the suction tubing once the compressor is assembled. During operation of the compressor, stress on the suction tubing in contact with the housing produces unwanted noise.
The alignment problems discussed herein have been addressed by several prior art devices. For instance, a suction line adaptor is known which comprises a pair of L-fittings respectively attached to the housing and the crankcase at axially spaced locations thereon, and a connecting tube inside the housing between the pair of L-fittings axially perpendicular to and disposed between the housing and the crankcase. The connecting pipe is capable of moving relative to one or both of the L-fittings to compensate for variations in radial and axial spacing between the housing and the crankcase. A problem with such a suction tube adaptor is that space is required between the crankcase and the housing sidewall within the housing.
Another common prior art approach to compensating for radial spacing between the housing and the inlet aperture in the compressor crankcase is the provision of an O-ring seal within the inlet opening to allow a suction tube end to variably penetrate into the aperture. Typically in this approach, an adaptor at the housing aperture is welded to the housing and brazed to the tubing.
Another prior art suction tube adaptor directed to compensating for spacing variations between the housing and the compressor crankcase comprises a tube entering radially inwardly from the housing sidewall having a slotted conical flange at the end thereof to abut against the crankcase in the general area of the suction inlet aperture. The divergent end of the conical flange has a diameter greater than the suction inlet aperture, thereby permitting alignment variations.
It is known in the prior art to provide filtering means within a refrigeration system, and more particularly in a compressor assembly, in order to filter out impurities and liquid gas refrigerant fed to the compressor assembly through the suction line. Known filtering means are overly complicated and often involve a centrifuging action. Also, suction accumulators often perform this filtering function by providing a screen member in the accumulator housing or on the end of a suction tube entering the suction accumulator. Such a screen member is not easily removed from the suction accumulator assembly for cleaning.
With respect to suction line adaptors for use in an indirect suction hermetically sealed compressor assembly, i.e., where the suction gas enters into the interior space of the housing, a suction line adaptor device is known which is attached to the housing as by welding. This adaptor comprises two pieces, one of which is welded to the housing at the location of the aperture therethrough, and the other being a coupling member attachable to a refrigeration system suction line as by brazing or the like. The coupling member with suction line attached thereto is then screwed onto the fitting welded to the housing for sealing engagement therewith. A nut threadedly engages each of the two components and brings them forcibly together at a surface to surface juncture having an O-ring sea seated therebetween.